At 25 weeks pregnant, you are in your sixth month of pregnancy, but you haven’t completed it yet. Weeks 25 through 28 make up the sixth month, so at 25 weeks you’re just entering that milestone. The confusion is understandable: pregnancy math is surprisingly tricky because months and weeks don’t divide evenly.
Why Weeks and Months Don’t Line Up Neatly
Most calendar months are 30 or 31 days, which works out to roughly 4.3 weeks per month, not a clean 4. That fraction adds up over the course of pregnancy. If you simply divided 25 weeks by 4, you’d get 6.25 months, which sounds like you’re past the six-month mark. But because each month is slightly longer than four weeks, 25 weeks actually lands at the beginning of month six, not the end of it.
Pregnancy itself is counted from the first day of your last menstrual period, which means it runs about 40 weeks total, or closer to 10 calendar months rather than the “nine months” people casually reference. That extra time is baked in from the start, since conception typically happens about two weeks after that first day. So throughout pregnancy, the week count will always feel like it’s running a bit ahead of the month count.
Where 25 Weeks Falls in the Trimesters
At 25 weeks, you’re in the final stretch of the second trimester. The second trimester spans weeks 13 through 28, so you have about three weeks left before crossing into the third trimester. This is a period of rapid growth for the baby and noticeable physical changes for you.
What Your Baby Is Doing at 25 Weeks
By 25 weeks, your baby’s senses are coming online in a meaningful way. At this stage, your baby may move in response to familiar sounds, including your voice. Rapid eye movements started a couple of weeks earlier, and the sucking reflex has been developing since around week 21.
The lungs are still maturing. Starting around week 23, the lungs begin producing surfactant, a substance that allows the tiny air sacs to inflate properly and keeps them from collapsing. This process is far from finished, and the lungs will continue developing well into the third trimester. The skin at this point is still wrinkled and somewhat see-through, with a pinkish or reddish tint from blood vessels showing through. A protective waxy coating has been covering the skin since around week 19, held in place by a layer of fine, downy hair. Fat is starting to accumulate, which will gradually smooth out the wrinkled appearance over the coming weeks.
If a Baby Is Born at 25 Weeks
A baby born at 25 weeks is extremely premature, but survival rates have improved significantly. Data from 2020 to 2022 published by the American Academy of Pediatrics shows an 82% survival rate for infants born at 25 weeks who receive care in a neonatal intensive care unit. Nearly all babies born at this gestational age (99.8%) receive active life support after delivery.
Survival, however, doesn’t tell the whole story. About 43% of 25-week survivors go home without severe complications. Among those who do survive, the median hospital stay is 110 days, roughly three and a half months. At discharge, about 45% still need supplemental oxygen and monitoring equipment at home. These numbers reflect how much development still needs to happen between 25 weeks and full term.
What You Might Be Feeling
Physically, 25 weeks brings a mix of changes that are hard to ignore. Your uterus is large enough that your healthcare provider can measure the distance from your pubic bone to the top of it (called fundal height) to track growth. Back pain is common as your center of gravity shifts and hormonal changes loosen your joints. You may also notice Braxton Hicks contractions, a mild tightening of the belly that comes and goes, especially in the evening or after physical activity. These are not labor contractions, just your uterus practicing.
Skin changes are typical at this stage. Stretch marks may appear on your belly, breasts, thighs, or buttocks. Some women develop darker patches on the face or a dark vertical line running down the belly. Tiny spider veins can show up on the face and legs. Hormonal shifts also increase blood volume, which can cause nasal congestion and nosebleeds, bleeding gums when brushing, dizziness, and nighttime leg cramps.
Tests Coming Up Around This Time
If you haven’t already, you’ll likely have a glucose screening test sometime between 24 and 28 weeks. This checks for gestational diabetes by measuring how your body handles sugar. The test may be scheduled earlier if you have risk factors for diabetes or if routine urine tests have shown elevated glucose levels. Your provider will let you know whether you need the standard one-step screening or a more detailed follow-up.